<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <script type="text/javascript" src="../../day03_jQuery/script/jquery-1.7.2.min.js"></script>
    <script type="text/javascript">
        $(function () {
            $("#btnId").click(function () {
                //获取第一个文本框的Value属性
                alert($(":text:first").val());

            });
        });
    </script>
</head>
<body>
<input type="text">
<input type="text">
<input type="text">
<input type="text">
<input type="button" value="点击" id="btnId">
</body>
</html>